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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

37070 results found.

  1. EP260623a: KAIT optical observations
  2. GRB 260708A: GRANDMA Optical Observations
  3. GRB 260710A: Insight-HXMT/HE detection
  4. GRB 260708A: LCO optical observations
  5. GRB 260710A: Fermi GBM Detection
  6. GRB 260709A: SVOM/GRM detection
  7. GRB 260709A: GECAM-B observation
  8. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  9. GRB 260705C: AstroSat CZTI detection
  10. GRB 260710A: Fermi GBM Final Real-time Localization
  11. GRB 260708A: Glowbug gamma-ray detection
  12. GRB 260704A: SVOM/ECLAIRs refined analysis
  13. GRB 260706A : GRANDMA Upper limits
  14. GRB 260708A: Kilonova-Catcher optical afterglow detection
  15. GRB 260708A: GECAM-B observation of a burst
  16. GRB 260708A: Fermi-GBM observation
  17. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  18. GRB 260709A: Fermi GBM Final Real-time Localization
  19. GRB 260708A: Fermi-LAT detection
  20. GRB 260705B: SVOM/GRM observation
  21. GRB 260708A: Fermi-GBM detection
  22. GRB 260706A: Further EP-FXT follow-up observation
  23. GRB 260706A: SVOM/VT optical upper limits
  24. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  25. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  26. GRB 260705C: Glowbug gamma-ray detection of a short burst
  27. GRB 260706A: SVOM/ECLAIRs refined analysis
  28. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  29. GRB 260706A: SVOM/GRM observation
  30. GRB 260706A: REM optical/NIR observations
  31. IceCube-260704A: No candidates from the Zwicky Transient Facility
  32. GRB 260706A: LCO optical upper limit
  33. GRB 260706A: EP-FXT follow-up observation
  34. GRB 260707A: Fermi GBM Final Real-time Localization
  35. GRB 260706A: Fermi GBM Observation
  36. IPN triangulation of GRB 260627A
  37. GRB 260705A: SVOM/ECLAIRs refined analysis
  38. GRB 260706A: SVOM detection of a burst
  39. GRB 260706A: Fermi GBM Final Real-time Localization
  40. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  41. GRB 260705A: LCO optical upper limits
  42. GRB 260704A: NOT optical upper limits
  43. GRB 260705C: Fermi GBM Final Localization
  44. GRB 260705B: Fermi GBM Final Real-time Localization
  45. Fermi GBM Sub-Threshold Detection of GRB 260705A
  46. GRB 260705A: SVOM detection of a burst
  47. GRB 260704A: EP-FXT follow-up observation
  48. GRB 260629A: SVOM/GRM observation of a short burst
  49. GRB 260629A: GECAM-A observation of a short burst
  50. GRB 260629A: AstroSat CZTI detection
  51. GRB 260704A: SVOM detection of a possible GRB
  52. GRB 260703B: Fermi GBM Final Localization
  53. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  54. Fermi GRB 260703A: Global MASTER-Net observations report
  55. GRB 260703A: Fermi GBM Final Localization
  56. GRB 260610B: VLA detection
  57. GRB 260623A: Glowbug gamma-ray detection
  58. GRB 260614B: ATCA Radio Upper Limits
  59. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  60. GRB 260701A: Fermi GBM Final Real-time Localization
  61. Fermi GBM trigger 804552016/260630945 is not a GRB
  62. GRB 260629A: Fermi GBM Final Real-time Localization
  63. Fermi GRB 260628A: Global MASTER-Net observations report
  64. GRB 260628A: Fermi GBM Final Real-time Localization
  65. Konus-Wind detection of GRB 260623B / EP260623a
  66. GRB 260618A: Fermi GBM Observation
  67. MASS-Cube (GRID 2.0) detection of GRB 260616B
  68. GRB 260619A: SVOM/ECLAIRs refined analysis
  69. Fermi GBM trigger 804010507/260624677 is not a GRB
  70. Konus-Wind detection of GRB 260618B
  71. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  72. GRB 260624A: Fermi GBM Final Real-time Localization
  73. GRB 260617A: Glowbug gamma-ray detection of a short burst
  74. IPN triangulation of GRB 260605A
  75. EP260623a: Optical follow-up observations with Kinder
  76. GRB 260623A: Fermi GBM Final Real-time Localization
  77. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  78. GRB 260614B: EP-FXT follow-up observation
  79. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  80. GRB 260619A: NOT optical observations
  81. GRB 260618B: LCO optical observations
  82. EP260618a: JinShan optical observations
  83. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  84. GRB 260618B: Fermi GBM Observation
  85. GRB 260619A: TRT optical counterpart confirmation
  86. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  87. GRB 260604B: 239Alferov CubeSat detection
  88. GRB 260604A: 239Alferov CubeSat detection
  89. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  90. GRB 260619A: SVOM/VT optical counterpart confirmation
  91. GRB 260618B: SVOM/VT optical candidate
  92. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  93. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  94. Konus-Wind detection of GRB 260617A
  95. GRB 260616B: AstroSat CZTI detection
  96. GRB 260616A: AstroSat CZTI detection
  97. GRB 260616A: SVOM/GRM observation
  98. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  99. GRB 260619A: Kilonova-Catcher optical upper limit
  100. EP260618a: EP-FXT follow-up observation

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